Car-lighting system.



residing UNITED STATES PATENT orrron;

HARRY D, ROHMAN, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO J.

STONE & COMPANY, LIMITED, 01

nnr'rronn, N LAND.

CAB-LIGHTING SYSTEM.

To all whom it may concern:

Be it known that I, HARRY D. ROHMAN, a citizen of the Republic of Switzerland, at New York city, in the county of New York and State of New York, have invented certain new and useful Improvements in Car-Lighting Systems, of which the following is a specification.

This inventionrelates to axle lighting and heating systems, such for example as car lightin systemsv and automobile starting and lig ting apparatus, and it'hasgfor one of its primary objects the provision of an improved battery overcharge preventing device whi'ch is simple in construction and operation and which dispenses with electromagnetic and other complicated forms of operating means therefor. Another of the primary objects of my invention resides in the provision of a novel means whereby the field of the dynamo is reversed on reversals of direction of rotation by separam excitation, although the dynamo is primarily of the self-exciting type.

My invention also contemplates the provision of means whereby the dynamo will still supply the lamps, if the overchar e preventing mechanism operates while t e train 1s running and the lamps are on.

The foregoing, together with such other objects as may hereinafter appear, or are.

incident to my invention, Iattain by means of a construction an arran ement dia am matically indicated in the accompanying drawing, in which the figure is a schematic diagram of my invention as applied to a car lighting system, the translating devices, such as lamps, fans, etc., being, however, not shown, as they do not, per 86, form a part of the present invention.

I will describe, myinvention as applied. to a car lighting system in which a dynamo of'the sli in belt type is employed. Beferring n r t% the drawing, 7, denotes the commutator of such a dynamo which, it will be readily understood, is driven Ifby a belt from a car axle'pulley, which belt passes over a pulley on the armature shaft, the tension of the belt being such that it will slip on the armature pulley when the train reaches the speed at which the dynamo is constructed to give fullfoutput. In prac-.

tice this train speed is about 15 or 20 miles g which is connected to the batteries by means 0f a branch wire 29 and resistance 30, this per hour, and after'such a train speed has been attained, the belt will slip on the Specification of Letters Patent. Application flied September 18, 1916, Serial No.

armature Patented nee. 31,1918. 120,698,

pulley and thereafter the armature will rotate at a substantially uniform rate of speed, regardless of train speeds. Mounted adjacent to the commutator is arocking commutation lead and to efi'ect the completion of certain circuits, as will further appear.

he positive main 12 which leads to the batteries 13 and to the translating devices 13 is connected to the right hand brush rocker arm 9, and the negative return lead 14 from the batteries and translating devices is connected to the left hand brush rocker arm 9. A suitable changeover switch A is provided for changing over the batteries alternately from charging to discharging position. Between the dynamo and the change-over switch A is located an automatic cut-in and out switch B which may be of any preferred type, designed to close when the dynamo voltage shall be equal to or .greater than the battery voltage in order to prevent a reverse flow.

The brush rocker 8 is provided with two upstanding arms or armatures 15 and 16, between which is located a clutch magnet 1?, the operating coil 18 of which is in shunt across the dynamo by means of the wire 19 connected to positive main 12, and wire 20 connected to negative brush rocker arm 9.

- The coil 18 is calibrated so as to operate at a lower voltage than the voltage at which the. cut-in switch B operates. 1

Mounted in juxtaposition to the commutator and brush rocker are two pairs of stationary contact brushes 21 and 21' and 22 and 22. The dynamo is of the'shunt wound type and I have indicated the field thereof at 23, the field being connectedto the brushes 21 and 22 by wire 24: and terminal 25, and to brushes 21' and 22 by 26 and terminal 27. Mounted on the ositive or right hand brush rocker arm 9, ut insulated therefrom, is a contact 28 negative brush 11. The

resistance preferably consisting of two units. It is divided into units by ewire 31 which leads from an ampere hour meter C located in the negative or return lead 14. The circuit of the branch 31 is normally intercepted at the contacts on the ampere hour meter, and is closed by the needle of the ampere hour meter when the needle bridges the said contacts.

The operation of the system is as follows, assuming that the train has come to a stop after having been traveling in a direction causing the commutator to rotate clockwise. Upon starting of the train in the opposite direction, the commutator is moved in the direction of the arrow and the friction of the brushes 10 and 11 on the commutator moves the brush rocker to the position shown in the drawing, in which position armature 15 of the brush rocker lies in close proximity to the clutch magnet 17 contact 28 engages brush 22 and negative contact arm 9 engages brush 21. The field 23 now receives a faint current from the batteries 13 through resistance 30, wire 29, contact 28, brush 22, terminal 25, wire 24, wire 26, terminal 27 brush 21, negative contact arm 9, and negative main 14: back to thebatteries. combined value of the two units of the resistance 30 is such that an amount of current can flow from the batteries suflicient to wipe out the residual magnetism of the field and reverse the field. Since the direction of rotation of the commutator has also been reversed, it will be seen that the signs of the brushes remain the same. With this faint exciting current from the batteries, the dynamo is able to generate a voltage sufficiently high to magnetize the clutch magnet 17 and cause it to attract the armature 15.

of the brush rocker. The coil 18 is preferably so constructed that it will perate at from 5 to 10 volts. 'When the brush rocker is pulled home by the clutch magnet, the spring resistance of the brushes 22 and 21' is overcome and contact is established between positive contact arm 9 and brush 21. When this occurs, the field 23 is connected across the armature as follows: positive brush 10, positive contact arm 9, brush 21, terminal 25, wire 24, wire 26, terminal 27, brush 21, negative contact arm 9 and brush 11. The dynamo is now self-exciting and can rapidly build up its voltage. When the dynamo voltage is equal'to or greater than that of the batteries, say for example,

80 volts, the switch B closes and the dynamo now delivers a useful current to the batteries and to the lamps if the lamps be on.

Charging of the batteries now continues inthe usual manner for a predetermined number of ampere hours, that is to say, until the needle of the ampere hour meter closes the branch circuit 31, after which the The operation f the system is as follows. If,

however, the train continues to run after the I ampere hour meter closes the branch 31, the

dynamo will still continue to charge the will move the brush rocker so that the right hand arm 9 will be out'of engagement with the brush 21. Further charging is thus prevented, and assuming that the train again starts running while the contacts of the ampere hour meter close the branch 31, the dynamo will be unable togenerate a voltage sufficient to cause the clutch magnet 17 to attract the armature 15 of the brush rocker, for the following reason. The current from the batteries will flow through the lower half of the resistance 30, (which is preferably iron wire andwhich has about the same ohmic value as the upper half of the resistance) through branch wire 31, ampere hour meter and negative 14 to the batteries and it is thus shunted away from the field, and no current from the armature can reach the field. As a result the dynamo cannot again begin to develop a' useful output until the contacts of the ampere hour meter are broken by the needle of the meter. When this occurs, of course the full amount of airrent capable of passing through the resistance 30 flows from the batteries to the field and the dynamo is again able to generate a voltage sufliciently high to energize the clutch magnet 17 and pull the brush rocker home, again making the dynamo self-exciting. It will be seen from the foregoing that while the batteries are thus insured a charge of at least a definite amount, harmful overcharging is prevented. An additional advantage of the arrangement is that the dynamo will in general be kept in operation while the lights are on and current will not be drawn in excessive amounts or.

for excessive periods from the batteries .to light the lamps, because even' though the ampere hour meter should close during the time. the generator is running, on stopping up and supply a useful output, as hereinbefore pointed out.

Itwill be understood, of course, that on reversals of direction of rotation the circuits will be made successively, in the manner just I pointed out, but in the reverse direction;

that the signs of the brushes will remain the same, as pomted out, because the current from the batteries will be sufficient to wipe Y obviated.

It will also be noted that while field magnetism is always maintained, thereby pre- -venting failures by keeping the dfynamo always in condition to develop use 111 output whenever it is called upon, yet the value of this fieldmagnetism is automatically altered to suit the service conditions, as pointed out. If desired, an automatic means may be employed for breaking the branch in which the resistance is located when the train is not running, in order to prevent even the small amount of leakage from the battery which would otherwise take place. As one means for accomplishing this result, I provide a governor mechanism D which operates a switch E, this switch being normally in open position but being immediately closed by the governor when the train begins to move.

I claim p 1. In a car lighting system, the combination of a dynamo, an accumulator, means for subjecting the field of the dynamo to the influence of the accumulator, and automatic means for shunting the current supplied by the battery to the field operable after the batteries have been charged a predetermined amount. I I

2. In a car lighting system, the combinatlon of a dynamo, an accumulator, a resistance in series between the accumulator and the field of the dynamo, and means forshunting the battery current around the field through a portion of said resistance, said means being dependent upon the state of aceumulator charge.

3. In a car lighting system, the combination of a dynamo, an accumulator, a resisance in series between the accumulator and the field of the dynamo, a branch adapted to shunt a portion of the current passing from the accumulator through said resistance, said branch being normally open, and means for closing said branch dependent upon the state of accumulator charge.

4. In a car lighting system, the combination of a dynamo, an accumulator, a resistance in series between the accumulator and the field of the dynamo, an ampere hour meter, and a circuit adapted to be closed by said ampere hour meter for shunting the current passing from the accumulator through said resistance.

5. In a car lighting system, the combination of a dynamo, an accumulator, a resistance in series between the accumulator and the field of the dynamo, an amperehour meter, and a circuit adapted to be closed by said ampere hour meter for shunting the current passing through said resistance, and connecting a portion of said resistance across the armature of the dynamo.

In testimony whereof I have hereunto signed my name.

HARRY D. ROHMAN.

from the accumulator. 

